Pipe joint gaskets including anti-slip segments for preventing the separation of interconnected, telescoping metal pipes in applications where a fluid such as water for fire mains is held under high pressure are known in the art. Exemplary gaskets are described in U.S. Pat. Nos. 5,295,697 and 5,464,228 in which a rubber gasket, serving as a fluid seal, includes toothed metal segments spaced around its inner perimeter. The toothed metal segments bite into the outer surface of the spigot of the inserted pipe and prevent withdrawal of the inserted pipe from a bell end of the other pipe, which can be caused by unbalanced hydrostatic or hydrodynamic forces. Hydrostatic and hydrodynamic forces that are unbalanced within a pipeline are referred to as thrust forces. Thrusts occur whenever there is a change in the direction of flow within a pipeline or the cross-sectional area of the pipeline. A shortcoming of restrained gaskets is that during fluid pressurization of the interconnected pipes, excessive axial thrust force generated by the resulting hydrostatic pressure can cause the acutely pointed, metal segments to exert destructive radial loads upon the inner axial surface of the bell end and the outer axial surface of the spigot end. In many instances, these radial loads are great enough to fracture the spigot and bell ends of the metal pipes.
Since toothed, anti-slip segments are known to destructively impinge upon metal pipes, the use of gaskets containing such or similar segments for preventing the separation of interconnected plastic pipes has been limited, especially in high pressure applications. Instead, plastic pipes, such as those formed from thermoplastic materials including polyethylene, polybutylene, polypropylene and poly(vinyl chloride) or PVC, are typically joined together by means of a bell-and-spigot gasket-sealed joint utilizing self-restrained gaskets often referred to as Rieber gaskets. A Rieber gasket consists of a continuous steel band either externally or internally bonded to an elastomer annular body. The Rieber gasket is locked into place within an annular groove of the bell, and the toothless steel band functions to prevent the gasket from becoming dislodged therefrom. The Rieber gasket fails however to sufficiently restrain axial separation of plastic pipes along a joint upon fluid pressurization of, or the occurrence of thrust forces within, the pipe joint at high pressure. Consequently, to restrain plastic pipes, external harness and other mechanical joint type glands must be used.
U.S. Pat. No. 9,400,073 describes a restrained pipe seal for sealing a joint between plastic pipes. The seal includes a plastic carrier member and a sealing member attached to the carrier member. The plastic carrier member includes retaining inserts for gripping a spigot of one pipe and a bell of another pipe for holding the pipes together against thrust forces, the inserts including multiple spigot teeth. Shortcomings of the pipe seal include both difficulty and expense related to manufacturing the seal. These shortcomings arise from requirements that the plastic carrier be made separately from the sealing member and then loaded into a rubber mold along with the retaining inserts. Further, the plastic carrier must also be of a sufficiently tough material to resist the heat of the gasket manufacturing process (vulcanizing process) which further increases the cost. Additionally, if the material of the plastic carrier is too inelastic, insertion of the pipe seal into a pipe bell may be prohibited.